Do I need an oil cooler?
 

I just bought a rebuilt 468 putting out about 500 HP. It came with a 11 quart oil pan but no cooler. With the large oil pan, is it necessary to have the oil cooler?

only if you want it to live. your marine engine is under constant load and generates a severe amount of heat. oil temp control of 210 to 240 is pretty standard now. if you checked yours after a hard run I guarrentee temp of close to 300.(bring the french fries). save yourself some headaches and buy a stock 500hp cooler setup with thermostat . oil also cools pistons and helps prevent detonation.